io::stringy(3)

NAME

IO-stringy - I/O on in-core objects like strings and
arrays

SYNOPSIS

IO::
::AtomicFile   adpO  Write a  file  which  is  updated
atomically     ERYQ
::Lines        bdpO  I/O handle to read/write to array
of lines   ERYQ
::Scalar       RdpO  I/O handle  to  read/write  to  a
string         ERYQ
::ScalarArray  RdpO  I/O handle to read/write to array
of scalars ERYQ
::Wrap         RdpO  Wrap old-style FHs in standard OO
interface  ERYQ
::WrapTie      adpO  Tie your handles & retain full OO
interface  ERYQ

DESCRIPTION

This toolkit primarily provides modules for performing
both traditional and object-oriented i/o) on things other
than normal filehandles; in particular, IO::Scalar,
IO::ScalarArray, and IO::Lines.

In the more-traditional IO::Handle front, we have
IO::AtomicFile which may be used to painlessly create
files which are updated atomically.

And in the "this-may-prove-useful" corner, we have
IO::Wrap, whose exported wraphandle() function will clothe anything that's not a blessed object in an IO::Handle-like
wrapper... so you can just use OO syntax and stop worrying
about whether your function's caller handed you a string,
a globref, or a FileHandle.

WARNINGS

Perl's TIEHANDLE spec was incomplete prior to 5.005_57; it
was missing support for "seek()", "tell()", and "eof()".
Attempting to use these functions with an IO::Scalar,
IO::ScalarArray, IO::Lines, etc. will not work prior to 5.005_57. None of the relevant methods will be invoked by
Perl; and even worse, this kind of bug can lie dormant for
a while. If you turn warnings on (via $^W or "perl -w"),
and you see something like this...: seek() on unopened file
...then you are probably trying to use one of these func tions on one of our IO:: classes with an old Perl. The remedy is to simply use the OO version; e.g.:: $SH->seek(0,0); ### GOOD: will work on any 5.005
seek($SH,0,0); ### WARNING: will only work on; 5.005_57 and beyond

INSTALLATION

Requirements

As of version 2.x, this toolkit requires Perl 5.005 for
the IO::Handle subclasses, and 5.005_57 or better is
strongly recommended. See "WARNINGS" for details.

Directions

Most of you already know the drill...: perl Makefile.PL
make
make test
make install
For everyone else out there... if you've never installed
Perl code before, or you're trying to use this in an envi
ronment where your sysadmin or ISP won't let you do inter
esting things, relax: since this module contains no binary extensions, you can cheat. That means copying the direc
tory tree under my "./lib" directory into someplace where
your script can "see" it. For example, under Linux:: cp -r IO-stringy-1.234/lib/* /path/to/my/perl/
Now, in your Perl code, do this:: use lib "/path/to/my/perl";
use IO::Scalar; ### or whatever
Ok, now you've been told. At this point, anyone who whines about not being given enough information gets an unflattering haiku written about them in the next change log. I'll do it. Don't think I won't.

VERSION

$Id: Stringy.pm,v 2.108 2001/08/20 20:36:15 eryq Exp $

TO DO

(2000/08/02) Finalize $/ support: Graham Barr submitted this patch half a year ago; Like
a moron, I lost his message under a ton of others, and
only now have the experimental implementation done.; Will the sudden sensitivity to $/ hose anyone out
there? I'm worried, so you have to enable it explic
itly in 1.x. It will be on by default in 2.x, though
only IO::Scalar has been implemented.
(2000/09/28) Separate read/write cursors?: Binkley sent me a very interesting variant of
IO::Scalar which maintains two separate cursors on the
data, one for reading and one for writing. Quoth he:

Isn't it the case that real operating system file

descriptors
maintain an independent read and write file posi

tion (and
seek(2) resets them both)?; (My answer: perhaps, but stdio's fseek/ftell manpages
seem to imply a single file position indicator, and
I'm trying to be IO::-ish.) Binkley also pointed out
some issues with his implementation:

For example, what does eof or tell return? The

read position or
the write position? (I assumed read position was

more important).; Your opinions on this are most welcome. (Me, I'm just
squeamish that this will break some code which depends
on the existing behavior, and that attempts to main
tain backwards-compatibility will slow down the code.)
(2001/08/08) Remove IO::WrapTie from new IO:: classes: It's not needed. Backwards compatibility could be
maintained by having new_tie() be identical to new(). Heck, I'll bet that IO::WrapTie should be reimple
mented so the returned object is just like an
IO::Scalar in its use of globrefs.

CHANGE LOG

Version 2.108 (2001/08/20): The terms-of-use have been placed in the distribution
file "COPYING". Also, small documentation tweaks were
made.
Version 2.105 (2001/08/09): Added support for various seek() whences to
IO::ScalarArray.; Added support for consulting $/ in IO::Scalar and
IO::ScalarArray. The old "use_RS()" is not even an
option. Unsupported record separators will cause a
croak().; Added a lot of regression tests to supoprt the above.; Better on-line docs (hyperlinks to individual func
tions).
Version 2.103 (2001/08/08): After sober consideration I have reimplemented
IO::Scalar::print() so that it once again always seeks to the end of the string. Benchmarks show the new
implementation to be just as fast as Juergen's con
tributed patch; until someone can convince me other
wise, the current, safer implementation stays.; I thought more about giving IO::Scalar two separate
handles, one for reading and one for writing, as sug
gested by Binkley. His points about what tell() and
eof() return are, I think, show-stoppers for this fea
ture. Even the manpages for stdio's fseek() seem to imply a single file position indicator, not two. So I think I will take this off the TO DO list. Remedy:
you can always have two handles open on the same
scalar, one which you only write to, and one which you
only read from. That should give the same effect.
Version 2.101 (2001/08/07): Alpha release. This is the initial release of the "IO::Scalar and friends are now subclasses of IO::Han
dle". I'm flinging it against the wall. Please tell
me if the banana sticks. When it does, the banana
will be called 2.2x.; First off, many many thanks to Doug Wilson, who has provided an invaluable service by patching IO::Scalar and friends so that they (1) inherit from IO::Handle,
(2) automatically tie themselves so that the "new()"
objects can be used in native i/o constructs, and (3)
doing it so that the whole damn thing passes its
regression tests. As Doug knows, my globref Kung-Fu
was not up to the task; he graciously provided the
patches. This has earned him a seat at the Co-Authors
table, and the right to have me address him as sensei.; Performance of IO::Scalar::print() has been improved by as much as 2x for lots of little prints, with the
cost of forcing those who print-then-seek-then-print
to explicitly seek to end-of-string before printing
again. Thanks to Juergen Zeller for this patch.; Added the COPYING file, which had been missing from
prior versions. Thanks to Albert Chin-A-Young for pointing this out.; IO::Scalar consults $/ by default (1.x ignored it by
default). Yes, I still need to support IO::ScalarAr
ray.
Version 1.221 (2001/08/07): I threatened in "INSTALLATION" to write an unflatter
ing haiku about anyone who whined that I gave them
insufficient information... but it turns out that I
left out a crucial direction. D'OH! Thanks to David Beroff for the "patch" and the haiku...

Enough info there?
Here's unflattering haiku:

Forgot the line, "make"! ;-)
Version 1.220 (2001/04/03): Added untested SEEK, TELL, and EOF methods to
IO::Scalar and IO::ScalarArray to support correspond
ing functions for tied filehandles: untested, because
I'm still running 5.00556 and Perl is complaining
about "tell() on unopened file". Thanks to Graham Barr for the suggestion.; Removed not-fully-blank lines from modules; these were
causing lots of POD-related warnings. Thanks to Nico_ las Joly for the suggestion.
Version 1.219 (2001/02/23): IO::Scalar objects can now be made sensitive to $/ .
Pains were taken to keep the fast code fast while
adding this feature. Cheers to Graham Barr for sub_ mitting his patch; jeers to me for losing his email for 6 months.
Version 1.218 (2001/02/23): IO::Scalar has a new sysseek() method. Thanks again to Richard Jones.; New "TO DO" section, because people who submit
patches/ideas should at least know that they're in the
system... and that I won't lose their stuff. Please
read it.; New entries in "AUTHOR". Please read those too.
Version 1.216 (2000/09/28): IO::Scalar and IO::ScalarArray now inherit from IO::Handle. I thought I'd remembered a problem with this ages ago, related to the fact that these IO::
modules don't have "real" filehandles, but the problem
apparently isn't surfacing now. If you suddenly
encounter Perl warnings during global destruction
(especially if you're using tied filehandles), then
please let me know! Thanks to B. K. Oxley (binkley) for this.; Nasty bug fixed in IIOO::::SSccaallaarr::::wwrriittee(()). Apparently, the offset and the number-of-bytes arguments were, for
all practical purposes, reversed. You were okay if you did all your writing with print(), but boy was
this a stupid bug! Thanks to Richard Jones for find_ ing this one. For you, Rich, a double-length haiku:

Newspaper headline
typeset by dyslexic man

loses urgency

BABY EATS FISH is

simply not equivalent

to FISH EATS BABY; New sysread and syswrite methods for IO::Scalar. Thanks again to Richard Jones for this.
Version 1.215 (2000/09/05): Added 'bool' overload to '""' overload, so object
always evaluates to true. (Whew. Glad I caught this
before it went to CPAN.)
Version 1.214 (2000/09/03): Evaluating an IO::Scalar in a string context now
yields the underlying string. Thanks to B. K. Oxley (binkley) for this.
Version 1.213 (2000/08/16): Minor documentation fixes.
Version 1.212 (2000/06/02): Fixed IO::InnerFile incompatibility with Perl5.004.
Thanks to many folks for reporting this.
Version 1.210 (2000/04/17): Added flush() and other no-op methods. Thanks to Doru Petrescu for suggesting this.
Version 1.209 (2000/03/17): Small bug fixes.
Version 1.208 (2000/03/14): Incorporated a number of contributed patches and
extensions, mostly related to speed hacks, support for
"offset", and WRITE/CLOSE methods. Thanks to Richard Jones, Doru Petrescu, and many others.
Version 1.206 (1999/04/18): Added creation of ./testout when Makefile.PL is run.
Version 1.205 (1999/01/15): Verified for Perl5.005.
Version 1.202 (1998/04/18): New IO::WrapTie and IO::AtomicFile added.
Version 1.110: Added IO::WrapTie.
Version 1.107: Added IO::Lines, and made some bug fixes to
IO::ScalarArray. Also, added getc().
Version 1.105: No real changes; just upgraded IO::Wrap to have a
$VERSION string.

AUTHOR

Primary Maintainer: Eryq (eryq@zeegee.com). President, ZeeGee Software Inc (http://www.zeegee.com).
Co-Authors: For all their bug reports and patch submissions, the
following are officially recognized:

Richard Jones
B. K. Oxley (binkley)
Doru Petrescu
Doug Wilson (for picking up the ball I dropped,

and doing tie() right)
Go to http://www.zeegee.com for the latest downloads and on-line documentation for this module.
Enjoy. Yell if it breaks.

docs.sk

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